The Kgo vari volt (Kgo VV) is a battery with a passthrough feature. its what I got instead of a dedicated passthrough to use at my pc so i can save the other batteries charged for work/out of the house. the good part of the KGO is you can easily detach the cord to carry it around if not just sitting there.
but agreed with other post once you get started you will want at least 2 batteries, a charger (2 would be best, one for back up) and a few other supplies. it seems to be a lot of cash at first but suddenly once your done there not much to buy besides what you need to maintain your vaping, (juice,parts etc)
one of the easiest, foolproof setups for beginning is a couple of ego twists or vision spinner batteries and a vivi nova mini or full tank, proven to be reliable and not much fiddling around with parts.
couple of my fav stores are:
http://www.smoktek.com/
http://www.gotvapes.com/
http://www.ecigbestsave.com/default.asp
but there are many more out there so shop around, and keep askin questions
the juice is subjective, there are tons of venders, and even more flavors, the best thing to do is get sample packs. Im trying juice from everywhere but one of my fallback venders is:
http://thevaporroom.net/eliquids.html. they have great deals, free samples with every order, always sending coupons, sales on flavor of the week etc.
there are many others but I always consider them as their 10 pack sampler is where it all got started for me.
And in regards to the last part of your statement, i wouldnt go all out and try to get set up all at once for months on end untill you know what works and what you like, there is just too much stuff to learn, to try, and what you like now may not be how you feel in two weeks.